I had made the larger one in the last picture at a science professional development program at Roper Mountain Science Center in Greenville , SC. One of the teachers in the class said that she made them on a smaller scale with empty soda/water bottles so I thought I would give it a shot. Teacher Tips: - Have students bring in the bottles. Collect until you have enough. Kids love doing contributing to a project and mine always asked if we had enough yet. - I took all of the bottles home in a large trash bag and precut all the tops while watching tv (and made the drainage holes). I kept the top and base together by using small cut pieces of packaging tape so that students had a matching top and bottom (they would just take off the tape when we started the project). - I modeled what I did at home in front of the students in case they wanted to make one on their own at home. - Make extras of EVERYTHING (bottles and cut pieces of duct tape). - Pour aquarium gravel into a shoe box and have ...